The Texas Rangers and Washington agreed to a contract extension through the 2015 season, general manager Jon Daniels announced on Monday.

“I thought this was a foregone conclusion, this guy has been our leader through a lot of tremendous times,” Daniels said. “You’re talking about a tenured veteran guy who this team believes in and followed in some big-time battles. Lame-duck? I don’t really buy into that. That wasn’t really our thought process.”

Washington, 61, is going into his eighth season with the Rangers. He’s the winningest manager in franchise history, and has taken the team to its greatest heights by going to the World Series in 2010 and 2011. The Rangers have won at least 90 games the past four seasons under Washington, as he joins Tampa Bay’s Joe Maddon as the only other manager to accomplish that feat.

Washington has a career managing record of 611-524, all with the Rangers. The 611 wins since the 2007 season rank as the fourth-most by a manager.

“I’m very appreciative for the support that the Texas Rangers have given me since I’ve been here,” Washington said. “All I ever wanted to do was to go out there and be the best I can for the organization and the players.”

Washington became the Rangers’ 17th manager on Nov. 6, 2006 after serving on the Oakland Athletics major-league coaching staff for 11 seasons. Washington signed a two-year contract when he was hired with options for 2009 and 2010. Both of those options were picked up and he signed two-year extensions after the 2010 season and after the 2012 season.

Daniels declined to address the status of pitching coach Mike Maddux’s contract, which goes through this season.